mortar

(uncountable) A mixture of lime or cement, sand and water used for bonding building blocks.

(countable) A muzzle-loading, indirect fire weapon with a tube length of 10 to 20 calibers and designed to lob shells at very steep trajectories.

(countable) A hollow vessel used to pound, crush, rub, grind or mix ingredients with a pestle.

(countable) In paper milling, a trough in which material is hammered.